Cemented carbides are often employed as cutting tool bodies for machining various metals and alloys. Cemented carbides are attractive materials for metal cutting applications since carbide properties can be tailored to specific requirements of the cutting environment. For example, cemented carbides having small grain size and low binder content are suitable for applications requiring high hardness and abrasion resistance. Alternatively, cemented carbides having higher binder content exhibit desirable thermal shock resistance and are generally used in interrupted cut applications.
However, cemented carbides are not suitable for all metal working applications. In some applications, cemented carbides may chemically react with the metal or alloy being machined. Moreover, cemented carbides may be unsuitable for applications requiring high hot hardness and superior heat dispersal resulting from high feed rates and greater depths of cut. For these applications, sintered ceramic compositions are used as cutting tool bodies. Sintered ceramic bodies can exhibit chemical inertness, high abrasion resistance, high hot hardness and superior thermal properties for heat dissipation. Sintered ceramic bodies currently in use are largely based on alumina (Al2O3) and/or silicon nitride (Si3N4). Such materials provide enhanced high temperature properties relative to cemented carbides, thereby enabling reduced operating time to a finished part. Nevertheless, improvements to sintered ceramic substrates are necessary to meet the evolving demands of metal working applications, and a careful balance between competing properties is required when making compositional changes to sintered ceramic bodies in efforts to provide cutting tools with improved performance.